Their on, then off, then on-again relationship has given the standup couple plenty of material. They discuss oversharing on stage, comedy after cancellation, and explaining monogamy to their four kids 10 of the best shows at this year's Edinburgh fringe Comedians Jessie Cave and Alfie Brown have got a bright idea. They've been a couple on and off for 10 years but now have decided to start working together. First with…